In vehicle front end accessory drive systems, idler pulleys with ball bearings are used to route a drive belt for improved wrap on accessory pulleys and to reduce drive belt span lengths. Similar pulleys with ball bearings are also used in tensioners for maintaining the proper belt tension. Both are subject to the same problem. During cold starts at temperatures below about 20.degree. F., the pulleys sometimes produce an objectionable whining noise called hoot that lasts for about five to thirty seconds. Noises coming from the engine area can be very alarming to vehicle owners, particularly those who are mechanically challenged or uninformed about various sounds associated with engine and vehicle operation. The hoot only occurs during cold startup and is attributed to a lack of lubrication at the bearing contacting surfaces; namely, the interaction between the rolling balls, the inner raceway and the outer raceway. Accordingly, it will be appreciated that it would be highly desirable to have a method for lubricating the idler bearings so that the bearings remain lubricated at cold startup to eliminate the hoot noise.
Bearing assemblies have conventionally had contact surfaces coated to prevent rust, reduce friction or increase wear resistance. The rust preventive coating process is a complicated process requiring a phosphatized film. The process for increasing wear resistance uses plasma spray coating which requires special plasma equipment. One friction reducing process coats roller bearings with a lubricating paint that is insoluble in oil, but the paint requires time to dry and erodes quickly. Another friction reducing process uses bronze or molybdenum applied by thermal spraying. Unfortunately, the coating erodes during use; so, multiple layers in different colors must be used to gauge wear. Bearing assemblies have conventionally used coatings and coating processes that increase manufacturing time or are complicated requiring multiple coatings or numerous manufacturing steps to accomplish. It is desirable to permanently coat bearing surfaces to reduce friction and eliminate hoot using a relatively simple, inexpensive process.